When he mentions WWII prison camps.
Immediately the EU wallahs jump on the German Bashing treadmill.
But, wait, he might have been talking about Japan... He never mentioned Nazi, he never mentioned Germany he just said punishing an escapee "like some world war II movie".
If I were Boris I'd risk the Japanese wrath and say "I'd just been reading about the making of Tenko and it seemed like the obvious thing to say".....
Leaving the complainants looking like "foot in mouth" disease. Doubt he'll do it though. However, the point of parallels is to make a point. Boris made the point. If there are ruffled feathers they might want to go back and consider why there are ruffled feathers. I.e. if they hadn't done it then nobody would have been able to cast it up.
Honestly. I like Boris, he's good value. Plus it gives the press something to make fool of themselves about.